Hello there dude ! well first of all royal dwarf takes 8 - 9 weeks to fully mature ,maybe even more,that's considering many other factors which all together form the overall conditions your plant live in,first you could bend the tops,HST those mother fuckeres >>>>follow this link >>>>
www.youtube.com/watch you need more distance from that COB LED you have so HST
Type of LED Grow Light Distance From Plant
1W Bulbs at least 12″ (30cm)
3W or 5W Bulbs at least 18″ (45cm)
High Wattage (300W+) up to 30″ (75cm) or more
you really want to avoid light burn,that can stun your plant and you don't realy want that,take in mind ussualy the plant puts on the most weight in the last 2-3 weeks of flower
2nd at hand my friend,you need to give her dry days betwen watering(check soil by poking with finger in,if it's damp.wait one more day before waterinng,avoid feeding your plant when soil is completely dry
Well this i hope would clear out some issues of yours,the #1 culprit for your slow growth is the light distance my friend ! happy growing and munchies out ! 💪